This application is based upon and claims the benefit of priority from the prior Japanese Patent Applications No. 2000-173718, filed Jun. 9, 2000; and No. 2001-140279, filed May 10, 2001, the entire contents of both of which are incorporated herein by reference.
The present invention relates to a fuse programming circuit applied to a redundancy circuit for, for example, a semiconductor memory device and adapted to program fuses and antifuses to store defective addresses.
The semiconductor memory devices have been made higher in integration density and larger in capacity size and it has, therefore, been difficult to manufacture semiconductor chips in a defect-free state. For this reason, a redundancy circuit has normally been provided in the semiconductor chip to remedy defects. The redundancy circuit has a plurality of spare cells, for example, in a word line unit or in a bit line unit. In the case where any defective cell is present in the portion of the semiconductor chip, it is saved by replacing the defective cell with a spare cell. It is, therefore, possible to improve the yield of semiconductor chips and wafers.
The redundancy circuit has a fuse for storing any defective address. Conventionally, as such a fuse, use has been made of a laser fuse programmed by a laser beam. In recent times, there has been a tendency toward using a current cut-off type fuse programmed by cutting off its current path by being supplied with a current as well as a current short-circuiting type antifuse programmed by short-circuiting its current path by being supplied with a current. In order to program the current cut-off type and current short-circuiting type fuses, it is necessary to flow a relatively large current of about 10 mA under a high voltage of about 10V. The programming of such a fuse is described, for example, in J. S. Choi, et al., xe2x80x9cAntifuse EPROM Circuit for Field Programmable DRAMxe2x80x9d, ISSCC Digest of Technical Papers, pp. 406-407.
Further, the redundancy circuit has many fuses. A decoder and switch circuit adapted to be turned ON/OFF in accordance with an output signal of the decoder are so used as to select a fuse to be programmed from a plurality of fuses. Upon being supplied with a fuse address signal, the decoder produces an output signal for selecting one of a plurality of fuses in accordance with the fuse address signal. In this case, a corresponding switch circuit is turned ON, so that a high voltage/large current is supplied to a fuse connected to the switch circuit to allow the fuse to be programmed.
Incidentally, a high number of fuses have been used due to the tendency towards a higher capacity of the semiconductor memory device and a high number of switch circuits are used to select such fuses.
Further, in the conventional redundancy circuit, the switch circuit is comprised of a MOSFET and bipolar transistor. The MOSFET and bipolar transistor are made larger in size so as to control the high voltage/large current involved. In the case where many switch circuits are configured by the MOSFETs and bipolar transistors, a larger space is required to arrange such switch circuits. In the case where, in order to prevent an increase in chip area, the MOSFET and bipolar transistor in the switch circuit are made smaller in size than normal, it is difficult to flow a high voltage/large current for programming the fuse. It is, therefore, not possible to positively program the fuse involved. This causes a fall in yield.
It is accordingly the object of the present invention to provide a fuse programming circuit which can prevent an increase in chip area and positively program fuses.
The object of the present invention is achieved by the following circuit.
That is, the fuse programming circuit comprises a fuse having first and second ends and programmed in accordance with a current supplied, the first end being connected to a first power supply; a thyristor having first and second electrodes and a gate electrode, the first electrode being connected to the second end of the fuse and the second electrode being connected to a second power supply lower in potential than the first power supply; and a control circuit having an input terminal supplied with an input signal and an output terminal connected to the gate electrode of the thyristor, the control circuit generating a control signal in accordance with the input signal which is supplied to the gate electrode of the thyristor to turn the thyristor ON.
The object of the present invention is achieved by the following circuit.
That is, the fuse programming circuit comprises a fuse having first and second ends and programmed in accordance with a current supplied, the first end being connected to a first power supply; a thyristor having first and second electrodes and gate electrode, the first electrode being connected to the second end of the fuse and the second electrode being connected to a second power supply lower in potential than the first power supply; and a control circuit having an input terminal supplied with an input signal and an output terminal connected to the gate electrode of the thyristor, the control circuit generating a control signal in accordance with the input signal which is supplied to the gate electrode of the thyristor to turn the thyristor ON.
Further, the object of the invention is achieved by the following circuit.
That is, the fuse programming circuit comprises a plurality of fuses having first and second ends and programmed in accordance with a current supplied, the first end of the respective fuse being connected to a first power supply; a plurality of thyristors having first and second electrodes and first and second gate electrodes, the first electrode of the respective thyristor being connected to the second end of the corresponding fuse and the second electrode being connected to a second power supply lower in potential than the first power supply; and a control circuit having an input terminal supplied with an input signal and a plurality of output terminals connected to the first and second gate electrodes of the respective thyristor, the control circuit generating a control signal for selecting one of these thyristors in accordance with the input signal.
The present invention can be applied to a fuse whose current path is cut off in accordance with a current supplied or an antifuse whose current path is short-circuited in accordance with a current supplied.
According to the present invention, the fuse is programmed with the use of a thyristor. This thyristor, though being smaller in size than the MOSFET and bipolar transistor, can control a high voltage/large current and, therefore, it can prevent the necessity to increase the chip area and is able to positively program fuses.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.